mtd: Handle possible -EPROBE_DEFER from parse_mtd_partitions()

mtd: Handle possible -EPROBE_DEFER from parse_mtd_partitions()

There are chances that the parse_mtd_partitions() function will return
-EPROBE_DEFER in mtd_device_parse_register(). This might happen when
the dependency is not available for the parser. For instance, on SDX55
the MTD_QCOMSMEM_PARTS parser depends on the QCOM_SMEM driver to parse
the partitions defined in the shared memory region. With the current
flow, the error returned from parse_mtd_partitions() will be discarded
in favor of trying to add the fallback partition.

This will prevent the driver to end up in probe deferred pool and the
partitions won't be parsed even after the QCOM_SMEM driver is available.

Fix this issue by bailing out of mtd_device_parse_register() when
-EPROBE_DEFER error is returned from parse_mtd_partitions() function and
propagate the error code to the driver core for probing later.

Fixes: 5ac67ce36cfe ("mtd: move code adding (registering) partitions to the parse_mtd_partitions()")
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>